I am sorry to hear about the inconvenience. If Chrome is already up to date, and you have followed this guideline:
After you click on the camera icon, you should see a button that says 'Manage' under the microphone, please click on it and make sure your microphone has been selected. We recommend a wired headset over the in-built microphone.
If all is set properly, please try to disable any Chrome extension you might be using, any antivirus or VPN. If the problem continues, please try to open the course in an incognito page (right click on the Chrome icon and selecting 'New Incognito Window) and let us know if it works there.
If nothing works, please let us know and we can check with our tech support team.